In recent years, there has been a problem of how to prevent a third party from leaking, stealing, and improperly using given information. Moreover, if leakage of any given information occurs from an information processing system, it is desirable that an administrator of that system can surely track and obtain the cause of the leakage of the given information.
Therefore, there is a known method of tracing and obtaining the cause of the leakage by leaving histories in which an access has been made to the information that should be prevented from being leaked and referencing the histories in which the access has been made after the leakage (for example, refer to Japanese Unexamined Patent Publication (Kokai) No. 2004-118243, and Japanese Unexamined Patent Publication (Kokai) No. 2003-076662). According to this method, the cause of the leakage can be identified by user names in the access histories by referencing the access histories after the information has been leaked out once.